On the Vita's side, you have half a dozen or so potential million sellers: Madden, Fifa, LittleBigPlanet, Assassin's Creed, Call of Duty, PSASBR, and Ratchett and Clank. On the 3DS side, you have Paper Mario, Layton 5, Scribblenauts, and Epic Mickey.
Honestly, I'd almost say the Vita deserved to sell better this holiday except for one word: Mario. This is going to be a 2D Mario's first holiday season. The Vita has nothing to compete with that combined with already existing evergreen titles in addition to the new lineup.
well doest littlebigplanet compete with the 2D mario games? it actually provides more content then both of them combined (in any games defense LBP offers more content than any game in the world i think expect MMO's)